Yesterday I led another expedition out into the Gulf of the Farallones on the Outer Limits with Captain Jimmy and San Francisco Bay Whale Watching. These wildlife tours transit the waters of the Gulf of the Farallones National Marine Sanctuary and visit the southeast Farallon Island, then continue on to the continental shelf where the coastal plane drops into the abyss of the deep sea. Primarily billed as whale watching, these trips are really about the entire ecosystem, and when I’m aboard, we talk shark, because sharks are what I love, study, advocate and protect through my non-profit Sea Stewards.
I’m always amazed at how many San Franciscans are aboard and who have never been on the waters of the Sanctuary, much less out to the islands. The trips start with some trepidation about the weather, the wind and waves and the 27-mile transit to the islands. The nervousness fades as we immediately see several small harbor porpoises before we even cross beneath the Golden Gate. There are more of these shy cetaceans than I have ever seen, and local researcher Bill Keener of Golden Gate Cetacean Research confirms that the small dolphins have returned to the San Francisco Bay after an absence of approximately 65 years. Their recent foraging in the bay may be an indicator of the health of the ecosystem.
Clearing Point Bonita, we enter the shipping channel and begin our search for whales, but it is the pelagic seabirds that first greet us. We are currently experiencing a changing of the guard in the transition between seasons. The productive ecosystem off the coast of California has three oceanographic seasons: upwelling season in the spring and early summer; relaxation in the late summer and fall; the storm season in winter.
During the upwelling season (March-July), strong northwest winds and the south flowing California current combine with the earth's rotation to drive surface waters away from the shore. These surface waters are replaced by an upwelling of nutrient-rich deeper water from offshore. The nutrients become available for surface dwelling phytoplankton (microscopic marine algae). Phytoplankton form the foundation of this oceanic food web and the combination of nutrients and increased sunlight in spring initiates a bloom of life that radiates up the food web from small shrimp called krill to the great whales. An abundance of phytoplankton, zooplankton, and young fish are food for animals at higher levels of the marine food web. During the summer months endangered blue, humpback and other species of whales visit our National Marine Sanctuaries of Monterey, the Gulf of the Farallones and the Cordell Bank to feed on this abundance of krill. Here's a video from a summer trip. http://youtu.be/qfNu54GBOHU
Now, the season is in the relaxation mode, and the calm seas and sunny skies help relax the passengers as we watch pelagic and double-crested cormorants, arctic terns and marbled murrelets wing past. The islands are in sight, but no whales so far. With less food, the humpback whales are making their exit as the California gray whales enter our waters in their annual migration from the feeding grounds near Alaska to the warm lagoons of Baja California Mexico where they calve. The gray whale is a success story. Hunted to extinction in the Atlantic, and with a few hundred individuals in the eastern Pacific, protections afforded under the Marine Mammal Protection Act has allowed this population to increase to well over 20,000.
Mid-channel, we are alerted by another vessel, The Salty Lady, that they are onto humpback whales. Captain Jimmy turns back towards the mainland and we see four humpback whales slowly swimming south. After a half hour, we head back to the islands and soon sea a California gray whale engaging in what looks like feeding near the south side of the Island. Nearby are two shark-watching boats and I wonder if the divers inside the cage witness the whale.
Out near the continental shelf, we are joined by over one hundred Pacific white-sided dolphins and among them northern right whale dolphins. The large pod of dolphins swim alongside us, surfing the bow wave as they head north past Middle Rock and north Farallon Islands towards Point Reyes and the Cordell Bank.
Just as the great whales migrate, so too do the great white sharks which visit the islands during this season to feed. As we discuss sharks on our way back to San Francisco, I reflect that like the whales, we can protect them in our sanctuary, but we can't protect them as they transit the open sea in their great migrations.
Like the whales, sharks need protection locally and internationally and require shark sanctuaries, protection from fisheries on the high seas and at home, and shark finning banned worldwide. Perhaps one of the most important things we can do is to protect sharks that are reproducing and to protect nurseries like the southern California bight for white sharks and the San Francisco Bay for sevengill sharks, soupfin sharks and the smaller hound sharks that pup there. Through our Shark Steward program with The Turtle Island Restoration Network, we are now developing a San Francisco Shark Sanctuary to protect local sharks reproducing in the bay so that sharks will continue to swim the waters of California.